CN112322837B - Smelting process for efficient slagging and desulfurization of LF (ladle furnace) aluminum killed steel - Google Patents

Abstract

The invention discloses a smelting process for high-efficiency slagging and desulfurizing of LF (ladle furnace) aluminum killed steel, which comprises the following steps: s1, converter steelmaking, wherein the control range of the converter end point temperature 1610 and 1660 ℃; the adding amount of the scrap steel is less than or equal to 70 tons; and a strong bottom blowing mode is adopted in the later stage of converter blowing to enhance the stirring of a molten pool. According to the smelting process for efficient slagging and desulfurization of the LF aluminum killed steel, the tapping, argon blowing station and LF refining tasks of a converter are divided into different parts through process design adjustment, a 'three-in-one' refining process of the tapping, argon blowing station and LF refining is formed, the LF slagging work is moved forward, a rapid slagging process system is formulated, more than 80% of slagging slag materials are added in the tapping process through design optimization, and the slag materials are promoted to be melted by fully utilizing the tapping steel flow impact kinetic energy, the molten steel sensible heat and the ladle bottom argon blowing stirring kinetic conditions; the argon station adopts top-bottom strong stirring and a proper deoxidation process, slag is rapidly formed to promote steel slag reaction, top slag reduction pre-desulfurization is realized, and LF slagging desulfurization burden is reduced; and the LF target basically completes slagging and desulfurization tasks by once temperature rise.

Description

Smelting process for efficient slagging and desulfurization of LF (ladle furnace) aluminum killed steel

Technical Field

The invention relates to the technical field of smelting, in particular to a smelting process for efficient slagging and desulfurization of LF (ladle furnace) aluminum killed steel.

Background

The LF furnace refining is an important smelting process, slagging and desulfurization are one of main functions, and although the LF furnace refining can meet the requirement of producing steel grades with the sulfur content of below 20ppm, the refining process time of the working procedure is long, and the desulfurization rate has a space for further improvement. The longer refining period leads to the increase of power consumption, electrode consumption and argon consumption and the reduction of the service life of ladle refractory materials, and meanwhile, the frequent change of the casting speed also has great influence on the quality of casting blanks because of the occurrence of continuous casting pull-down production and even casting break accidents caused by node reasons. Compared with converter smelting and continuous casting processes, the treatment time of the current LF process becomes a bottleneck limiting the whole steelmaking process to realize the whole high efficiency.

In addition, from the trend of the standardization and the intellectualization of refining operation, the current LF operation mode mainly depends on the personal experience of operators, repeated slag formation by multiple times of strong stirring exists, the increase of the treatment period and the consumption is influenced, and the standardization and the intellectualization of refining operation are not beneficial to popularization. Therefore, from the aspects of shortening the smelting period, reducing the cost, reasonably distributing refining tasks such as slagging, desulfurizing and the like and promoting the standardization and intellectualization of refining operation, the efficient slagging and desulfurizing process of the LF path aluminum killed steel is needed to be developed.

Patent CN105950828A discloses a method for reducing smelting time of molten steel in an LF furnace, a certain amount of pre-prepared slag-making materials (containing 35-55% of lime, 35-40% of aluminium oxide powder, 12-20% of aluminium particles, 2-5% of metal calcium and 3-5% of silicon dioxide powder) are added in the tapping process, and after tapping is finished, 0.05-0.08 kg/ton of active metal Ca is added in the molten steel, so that S in the molten steel is replaced, the S content in the molten steel is reduced, and the LF desulfurization time is shortened. However, metallic calcium is an active element, and the addition of metallic calcium after the tapping of the converter is difficult to control and avoid oxidation, so that the desulfurization in the production process is unstable, and the production cost is increased.

Disclosure of Invention

Technical problem to be solved

Aiming at the defects of the prior art, the invention provides a smelting process for high-efficiency slagging and desulfurizing of LF (ladle furnace) aluminum killed steel, which realizes the purposes of early slagging, thorough slagging, early reduction of ladle top slag and high-efficiency refining by a 'three-in-one' refining process of converter tapping, an argon blowing station and LF refining, realizes the purposes of upgrading and standardizing the LF high-efficiency refining process, improving the process and LF desulfurization efficiency, and reducing economic and technical indexes such as LF refining operation time, power consumption, electrode consumption and the like.

(II) technical scheme

In order to achieve the purpose, the invention is realized by the following technical scheme: a smelting process for high-efficiency slagging and desulfurizing of LF (ladle furnace) aluminum killed steel comprises the following steps:

s1, converter steelmaking, wherein the control range of the converter end point temperature 1610 and 1660 ℃; the adding amount of the scrap steel is less than or equal to 70 tons; a strong bottom blowing mode is adopted in the later stage of converter blowing, so that the stirring of a molten pool is enhanced, the oxidability of top slag is reduced, and the terminal oxygen and terminal carbon content of the converter are reduced;

s2, carrying out infrared slag tapping detection in the tapping process, and strictly controlling the slag tapping amount of the converter by adopting a slag stopping cone and pneumatic slag stopping; alloy and auxiliary materials are added through a rotary trough during tapping 1/5, the rotary trough is dynamically adjusted to be aligned with steel flow during the adding process, the lime feeding speed is controlled, and the phenomenon that lime is added too fast to melt and lump is avoided. The adding sequence is as follows: pre-deoxidized carbon powder → aluminum particles → alloy → lime and bauxite; wherein the addition amount of the pre-deoxidized carbon powder is 0.1 kg/ton steel, lime, bauxite are added according to the oxygen determination result of a converter terminal sublance, the addition amount of the lime is 5.0-7.5 kg/ton steel, the addition amount of the bauxite is 0.35-1.0 kg/ton steel, the addition amount of the bauxite is 1.7-2.8 kg/ton steel, and all the addition is finished before the tapping is finished;

s3, argon is blown from the bottom of the ladle in the whole tapping process, strong bottom blowing is kept before alloy and slag are added, the slag in the ladle is prevented from being accumulated into large blocks, and the bottom blowing can be properly adjusted to be small after the slag is added;

s4, measuring temperature and determining oxygen after the argon blowing station enters the station, adding aluminum particles according to the oxygen determination result, wherein the adding amount of the aluminum particles is controlled according to the target range of the outbound Als component of 0.04-0.08%. After aluminum particles are added, opening the ladle and blowing the ladle from the bottom, blowing argon by a top gun and stirring, wherein the stirring strength is proper for preventing molten steel from splashing out of the ladle, lifting the top gun and measuring the temperature and determining oxygen to be discharged out of the station after the top and bottom argon blowing stirring is carried out for 3-6min, and stopping the ladle bottom argon blowing when the ladle is lifted;

and S5, opening the ladle bottom to blow argon after LF enters the station, wherein the argon blowing flow rate is 600 plus 1200Nl/min, adjusting the argon blowing flow rate to be 100 plus 250Nl/min after the slag layer is blown, and then measuring the temperature and sampling 1. Adding aluminum particles before heating, wherein the adding amount of the aluminum particles is controlled according to the Als component of the argon blowing station and the middle upper limit of the target value of the Als component of the steel type, and the adding amount of each ton of steel is 0-0.8 kg/ton;

s6, starting temperature rise, adjusting the bottom blowing flow to 400Nl/min, once raising the temperature to a slagging target temperature of 1600-1610 ℃ at the temperature rise rate of 4 ℃/min, adding lime when the secondary model calculation temperature reaches 1590 ℃, wherein the lime addition is determined according to the S content of the argon blowing station, and the steel addition per ton is 0-2.5 kg/ton;

s7, carrying out primary alloying after temperature rise is finished, fishing out a slag sample after strong stirring for 3min, observing, judging whether a proper amount of aluminum cutting pills or lime needs to be added or not according to the color and the section thickness of the slag sample, and finishing slagging when the slag sample is white, yellow-white or green-white;

s8, performing temperature measurement sampling 2 after slagging is finished, finely adjusting components to a target value according to the result of the sample 2, adding and stirring the alloy for 3min, heating at 5-15 ℃ above the target temperature, after heating is finished, performing weak stirring for 3min, starting to feed a calcium line of 380-450m and a wire feeding speed of 160-220m/min, performing weak stirring after wire feeding is finished, wherein the argon flow is 30-120Nl/min, the molten steel bright surface is controlled to be 150mm and the weak stirring time is not less than 8min, and then lifting the molten steel to a continuous casting table for casting.

(III) advantageous effects

The invention provides a smelting process for high-efficiency slagging and desulfurizing of LF (ladle furnace) aluminum killed steel. The method has the following beneficial effects:

according to the smelting process for efficient slagging and desulfurizing of the LF aluminum killed steel, the division of tapping, argon blowing stations and LF refining tasks of a converter is adjusted through process design, a 'three-in-one' refining process of tapping, argon blowing stations and LF refining of the converter is formed, the LF slagging work is moved forward, and a rapid slagging process system is established. Through design optimization, more than 80% of slagging slag is added in the tapping process, and slag melting is promoted by fully utilizing tapping steel flow impact kinetic energy, molten steel sensible heat and ladle bottom argon blowing stirring kinetic conditions; the argon station adopts top-bottom strong stirring and a proper deoxidation process, slag is rapidly formed to promote steel slag reaction, top slag reduction pre-desulfurization is realized, and LF slagging desulfurization burden is reduced; the LF target basically completes slagging and desulfurization tasks through once heating, the treatment period of the LF furnace is greatly shortened, slag consumption and energy consumption are reduced, and efficient refining process upgrading and standardized operation of the LF path aluminum killed steel are integrally realized.

Detailed Description

The described embodiments are only some embodiments of the invention, not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

A smelting process for high-efficiency slagging and desulfurizing of LF (ladle furnace) aluminum killed steel comprises the following steps:

s1, converter steelmaking, wherein the control range of the converter end point temperature 1610 and 1660 ℃; the adding amount of the scrap steel is less than or equal to 70 tons; a strong bottom blowing mode is adopted in the later stage of converter blowing, so that the stirring of a molten pool is enhanced, the oxidability of top slag is reduced, and the terminal oxygen and terminal carbon content of the converter are reduced;

s2, carrying out infrared slag tapping detection in the tapping process, and strictly controlling the slag tapping amount of the converter by adopting a slag stopping cone and pneumatic slag stopping; alloy and auxiliary materials are added through a rotary trough during tapping 1/5, the rotary trough is dynamically adjusted to be aligned with steel flow during the adding process, the lime feeding speed is controlled, and the phenomenon that lime is added too fast to melt and lump is avoided. The adding sequence is as follows: pre-deoxidized carbon powder → aluminum particles → alloy → lime and bauxite; wherein the addition amount of the pre-deoxidized carbon powder is 0.1 kg/ton steel, lime, bauxite are added according to the oxygen determination result of a converter terminal sublance, the addition amount of the lime is 5.0-7.5 kg/ton steel, the addition amount of the bauxite is 0.35-1.0 kg/ton steel, the addition amount of the bauxite is 1.7-2.8 kg/ton steel, and all the addition is finished before the tapping is finished;

s3, argon is blown from the bottom of the ladle in the whole tapping process, strong bottom blowing is kept before alloy and slag are added, the slag in the ladle is prevented from being accumulated into large blocks, and the bottom blowing can be properly adjusted to be small after the slag is added;

s4, measuring temperature and determining oxygen after the argon blowing station enters the station, adding aluminum particles according to the oxygen determination result, wherein the adding amount of the aluminum particles is controlled according to the target range of the outbound Als component of 0.04-0.08%. After aluminum particles are added, opening the ladle and blowing the ladle from the bottom, blowing argon by a top gun and stirring, wherein the stirring strength is proper for preventing molten steel from splashing out of the ladle, lifting the top gun and measuring the temperature and determining oxygen to be discharged out of the station after the top and bottom argon blowing stirring is carried out for 3-6min, and stopping the ladle bottom argon blowing when the ladle is lifted;

and S5, opening the ladle bottom to blow argon after LF enters the station, wherein the argon blowing flow rate is 600 plus 1200Nl/min, adjusting the argon blowing flow rate to be 100 plus 250Nl/min after the slag layer is blown, and then measuring the temperature and sampling 1. Adding aluminum particles before heating, wherein the adding amount of the aluminum particles is controlled according to the Als component of the argon blowing station and the middle upper limit of the target value of the Als component of the steel type, and the adding amount of each ton of steel is 0-0.8 kg/ton;

s6, starting temperature rise, adjusting the bottom blowing flow to 400Nl/min, once raising the temperature to a slagging target temperature of 1600-1610 ℃ at the temperature rise rate of 4 ℃/min, adding lime when the secondary model calculation temperature reaches 1590 ℃, wherein the lime addition is determined according to the S content of the argon blowing station, and the steel addition per ton is 0-2.5 kg/ton;

s7, carrying out primary alloying after temperature rise is finished, fishing out a slag sample after strong stirring for 3min, observing, judging whether a proper amount of aluminum cutting pills or lime needs to be added or not according to the color and the section thickness of the slag sample, and finishing slagging when the slag sample is white, yellow-white or green-white;

s8, performing temperature measurement sampling 2 after slagging is finished, finely adjusting components to a target value according to the result of the sample 2, adding and stirring the alloy for 3min, heating at 5-15 ℃ above the target temperature, after heating is finished, performing weak stirring for 3min, starting to feed a calcium line of 380-450m and a wire feeding speed of 160-220m/min, performing weak stirring after wire feeding is finished, wherein the argon flow is 30-120Nl/min, the molten steel bright surface is controlled to be 150mm and the weak stirring time is not less than 8min, and then lifting the molten steel to a continuous casting table for casting.

According to the invention, through reasonably designing the division of tapping, argon blowing station and LF refining tasks of the converter, the type proportion, the adding amount and the adding sequence of tapping alloy, slag charge of the converter are determined, the tapping rapid slagging process and the argon blowing station top-bottom stirring process are formulated, and the process parameters such as LF temperature rise and slag charge adding standard are formulated, so that slagging desulfurization work is advanced, the desulfurization rate in the tapping process of the converter is improved, the LF slagging desulfurization burden is reduced, and a 'three-in-one' refining process of the tapping, the argon blowing station and the LF refining is formed; the LF slagging and desulfurizing time, the ton steel power consumption and the slag charge consumption are all obviously reduced; the desulfurization rate and the total desulfurization rate in the processes of the converter, the argon blowing station and the LF are obviously improved; the buffering capacity of the LF procedure is increased, the reduction ratio of the casting machine caused by the nodes of the LF procedure is reduced by 1.39% in the same ratio, and the method has good economic benefit.

Example 1

The embodiment is a smelting method for efficient slagging and desulfurizing of LF aluminum killed steel in a process route of '300 t converter → argon blowing station → RH → continuous casting', the implementation steel type is SPHC, and the specific steps are as follows:

(1) converter steelmaking: 53.2 tons of scrap steel are fed into the furnace, and 272 tons of molten iron are fed into the furnace; the blowing end temperature of the converter is 1624 ℃, and the end oxygen is 546 ppm; the bottom blowing strength is increased in the later stage of converter blowing, and the stirring of a molten pool is enhanced;

(2) infrared slag tapping detection is utilized in the tapping process, a slag blocking cone and pneumatic slag blocking are adopted, and the slag tapping amount of the converter is strictly controlled; alloy and auxiliary materials are added through a rotary trough during tapping 1/5, the rotary trough is dynamically adjusted to be aligned with steel flow during the adding process, the lime feeding speed is controlled, and the phenomenon that lime is added too fast to melt and lump is avoided. The adding sequence is as follows: pre-deoxidized carbon powder → aluminum particles → alloy → lime and bauxite; wherein the addition amount of the pre-deoxidized carbon powder is 0.1 kg/ton steel, the addition amount of the lime is 7.13 kg/ton steel, the addition amount of the bauxite is 0.73 kg/ton steel, the addition amount of the aluminum particles is 2.27 kg/ton steel, and the addition is finished before the tapping is finished; the content of S at the end point of the converter is 0.0118%

(3) The bottom blowing argon of the ladle is opened in the whole tapping process, the strong bottom blowing is kept before the alloy and slag are added, the accumulation and agglomeration of the slag in the ladle are avoided, and the bottom blowing can be properly adjusted to be small after the slag is added;

(4) and (3) measuring the temperature and determining the oxygen after the argon blowing station enters the station, adding 0.22kg of aluminum particles per ton of steel according to the oxygen determination result, after the aluminum particles are added, opening the bottom of the steel ladle to blow and lower a top gun to perform top and bottom argon blowing stirring, wherein the stirring strength is proper for preventing molten steel from splashing out of the steel ladle, lifting the top gun after stirring for 4min, measuring the temperature and determining the oxygen, and stopping the argon blowing at the bottom of the steel ladle when the steel ladle is lifted. The contents of the molten steel [ Als ] and [ S ] discharged from the argon blowing station are respectively 0.045% and 0.0066%;

(5) opening a ladle bottom to blow argon gas after LF enters a station, wherein the argon blowing flow is 800Nl/min, adjusting the argon blowing flow to be 150Nl/min after a slag layer is blown, then measuring the temperature to be 1568 ℃, sampling 1, and adding 0.45 kg/ton of aluminum particles before heating;

(6) heating is started, the bottom blowing flow is adjusted to be 330Nl/min, the heating rate is 4 ℃/min, the temperature is once increased to the slagging target temperature 1603 ℃, and the lime addition amount at the later stage of heating is 0.60 kg/ton steel;

(7) after the temperature rise is finished, adding ferromanganese and carburant to adjust the components according to the target values, after strong stirring for 3min, adding lime 0.54 kg/ton of steel according to the observed slag sample condition, and continuing strong stirring for 5min to finish slag making;

(8) carrying out temperature measurement sampling 2 after slagging is finished, adding medium carbon ferromanganese, a recarburizing agent and aluminum particles according to the result of the sampling 2, adjusting the components to a target value, adding and stirring the alloy for 3min, then heating according to the outbound target temperature plus 5 ℃, starting to feed a seamless cored wire 389m after the heating is finished and weakly stirring for 3min, wherein the wire feeding speed is 200m/min, weakly stirring is carried out after the wire feeding is finished, the argon flow is 50Nl/min, the bright surface of the molten steel is controlled to be about 120mm, and lifting the molten steel on a continuous casting table for casting after the weakly stirring time is 9 min;

the content of the end point S is 0.0015%, the total desulfurization rate reaches 87%, and the desulfurization rate is improved by 17% compared with the original process. The smelting period is reduced by 6min, the power consumption per ton of steel is reduced, and the slag charge consumption is reduced.

Example 2

The embodiment is a smelting method for efficient slagging and desulfurizing of LF aluminum killed steel in a process route of '300 t converter → argon blowing station → RH → continuous casting', the implementation steel type is SPHC, and the specific steps are as follows:

(1) converter steelmaking: 60.8 tons of scrap steel are fed into the furnace, and 267 tons of molten iron are fed into the furnace; the blowing end temperature of the converter is 1656 ℃, and the end oxygen is 471 ppm; the bottom blowing strength is increased in the later stage of converter blowing, and the stirring of a molten pool is enhanced;

(2) infrared slag tapping detection is utilized in the tapping process, a slag blocking cone and pneumatic slag blocking are adopted, and the slag tapping amount of the converter is strictly controlled; alloy and auxiliary materials are added through a rotary trough during tapping 1/5, the rotary trough is dynamically adjusted to be aligned with steel flow during the adding process, the lime feeding speed is controlled, and the phenomenon that lime is added too fast to melt and lump is avoided. The adding sequence is as follows: pre-deoxidized carbon powder → aluminum particles → alloy → lime and bauxite; the adding sequence is as follows: pre-deoxidized carbon powder → aluminum particles → alloy → lime and bauxite; wherein the addition amount of the pre-deoxidized carbon powder is 0.1 kg/ton steel, the addition amount of the lime is 7.3 kg/ton steel, the addition amount of the bauxite is 0.64 kg/ton steel, the addition amount of the aluminum particles is 2.18 kg/ton steel, and the addition is finished before the tapping is finished; the content of the end point S of the converter is 0.024 percent

(3) The bottom blowing argon of the ladle is opened in the whole tapping process, the strong bottom blowing is kept before the alloy and slag are added, the accumulation and agglomeration of the slag in the ladle are avoided, and the bottom blowing can be properly adjusted to be small after the slag is added;

(4) and (3) measuring the temperature and determining the oxygen after the argon blowing station enters the station, adding 0.19kg of aluminum particles per ton of steel according to the oxygen determination result, after the aluminum particles are added, opening the bottom of the steel ladle to blow and lower a top gun to perform top and bottom argon blowing stirring, wherein the stirring strength is proper for preventing molten steel from splashing out of the steel ladle, lifting the top gun after stirring for 3min, measuring the temperature and determining the oxygen, and stopping the argon blowing at the bottom of the steel ladle when the steel ladle is lifted. The contents of [ Als ] and [ S ] of the molten steel discharged from the argon blowing station are respectively 0.088% and 0.0165%;

(5) opening a ladle bottom to blow argon after LF enters a station, setting the argon blowing flow at 800Nl/min, adjusting the argon blowing flow at 150Nl/min after a slag layer is blown, then measuring the temperature at 1575 ℃, sampling 1, and adding no aluminum particles before the temperature is raised according to the Als component of an outbound sample of the argon blowing station;

(6) starting to heat up, adjusting the bottom blowing flow to be 330Nl/min, and heating up to a slagging target temperature 1602 ℃ at one time at a heating rate of 4 ℃/min; after the temperature rise is finished, adding ferromanganese and carburant, adjusting the components according to the target value, and stirring for 3min to obtain white slag;

(7) carrying out temperature measurement sampling 2 after slagging is finished, adding aluminum particles according to the result of the sampling 2 to adjust the components to a target value, adding alloy, stirring for 3min, then heating according to the temperature of the target value +5 ℃, starting to feed seamless cored wires 397m after weak stirring for 3min after heating is finished, wherein the wire feeding speed is 200m/min, carrying out weak stirring after wire feeding is finished, the argon flow is 50Nl/min, the bright surface of molten steel is controlled to be about 120mm, and lifting the molten steel on a continuous casting table for casting after the weak stirring time is 10 min;

the content of the end point S is 0.0022 percent, the total desulfurization rate reaches 89 percent, and the desulfurization rate is improved by 19 percent compared with the prior art. The smelting period is reduced by 5min, the power consumption per ton of steel is reduced, and the slag charge consumption is reduced.

In conclusion, the smelting process for efficient slagging and desulfurizing of the LF aluminum killed steel adjusts the tapping, argon blowing station and LF refining tasks of the converter through process design, forms a 'three-in-one' refining process of the tapping, argon blowing station and LF refining of the converter, enables the LF slagging work to move forward, and establishes a rapid slagging process system. Through design optimization, more than 80% of slagging slag is added in the tapping process, and slag melting is promoted by fully utilizing tapping steel flow impact kinetic energy, molten steel sensible heat and ladle bottom argon blowing stirring kinetic conditions; the argon station adopts top-bottom strong stirring and a proper deoxidation process, slag is rapidly formed to promote steel slag reaction, top slag reduction pre-desulfurization is realized, and LF slagging desulfurization burden is reduced; the LF target basically completes slagging and desulfurization tasks through once heating, the treatment period of the LF furnace is greatly shortened, slag consumption and energy consumption are reduced, and efficient refining process upgrading and standardized operation of the LF path aluminum killed steel are integrally realized.

Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.

Claims (1)

1. The smelting process for efficient slagging and desulfurization of LF (ladle furnace) aluminum killed steel is characterized by comprising the following steps of:

s1, converter steelmaking, wherein the control range of the converter end point temperature 1610 and 1660 ℃; the adding amount of the scrap steel is less than or equal to 70 tons; a strong bottom blowing mode is adopted in the later stage of converter blowing, so that the stirring of a molten pool is enhanced, the oxidability of top slag is reduced, and the terminal oxygen and terminal carbon content of the converter are reduced;

s2, carrying out infrared slag tapping detection in the tapping process, and strictly controlling the slag tapping amount of the converter by adopting a slag stopping cone and pneumatic slag stopping; alloy, auxiliary material are added through rotatory silo during tapping 1/5, and the rotatory silo of addition process dynamic adjustment aims at the steel stream to control lime feed rate, avoid lime to add too soon and not too late to melt and lump together, add the order and be: pre-deoxidized carbon powder → aluminum particles → alloy → lime and bauxite; wherein the addition amount of the pre-deoxidized carbon powder is 0.1 kg/ton steel, lime, bauxite are added according to the oxygen determination result of a converter terminal sublance, the addition amount of the lime is 5.0-7.5 kg/ton steel, the addition amount of the bauxite is 0.35-1.0 kg/ton steel, the addition amount of the bauxite is 1.7-2.8 kg/ton steel, and all the addition is finished before the tapping is finished;

s3, argon is blown from the bottom of the ladle in the whole tapping process, strong bottom blowing is kept before alloy and slag are added, the slag in the ladle is prevented from being accumulated into large blocks, and the bottom blowing can be properly adjusted to be small after the slag is added;

s4, firstly measuring temperature and determining oxygen after an argon blowing station enters the station, adding aluminum particles according to an oxygen determination result, controlling the adding amount of the aluminum particles according to the target range of Als components of the station, namely 0.04-0.08%, after the aluminum particles are added, opening a ladle and blowing the ladle from the bottom, blowing argon by using a top gun, stirring, wherein the stirring strength is that molten steel does not splash out of the ladle, lifting the top gun after the argon is blown from the top and the bottom and stirring for 3-6min, measuring the temperature and determining oxygen, and stopping the argon blowing from the bottom of the ladle when the ladle is lifted;

s5, opening a ladle to blow argon from the bottom after LF enters a station, adjusting the flow of the argon to be 250Nl/min after the slag layer is blown, measuring the temperature and sampling 1, adding aluminum particles before heating, controlling the adding amount of the aluminum particles according to the Als component of the station of the argon blowing station and the upper limit of the target value of the Als component of the steel type, wherein the adding amount of steel per ton is 0-0.8 kg/ton;

s6, starting temperature rise, adjusting the bottom blowing flow to 400Nl/min, once raising the temperature to a slagging target temperature of 1600-1610 ℃ at the temperature rise rate of 4 ℃/min, adding lime when the secondary model calculation temperature reaches 1590 ℃, wherein the lime addition is determined according to the S content of the argon blowing station, and the steel addition per ton is 0-2.5 kg/ton;

s7, carrying out primary alloying after temperature rise is finished, fishing out a slag sample after strong stirring for 3min, observing, judging whether a proper amount of aluminum cutting pills or lime needs to be added or not according to the color and the section thickness of the slag sample, and finishing slagging when the slag sample is white, yellow-white or green-white;

s8, performing temperature measurement sampling 2 after slagging is finished, finely adjusting components to a target value according to the result of the sample 2, adding and stirring the alloy for 3min, heating at 5-15 ℃ above the target temperature, after heating is finished, performing weak stirring for 3min, starting to feed a calcium line of 380-450m and a wire feeding speed of 160-220m/min, performing weak stirring after wire feeding is finished, wherein the argon flow is 30-120Nl/min, the molten steel bright surface is controlled to be 150mm and the weak stirring time is not less than 8min, and then lifting the molten steel to a continuous casting table for casting.